Manufacture of lead-manganese



Patented May 10, 1938 UNITED STATES PATENT OFFiCE MANUFACTURE OFLEAD-MAN GAN ESE NAPHTHENATE No Drawing. Application January 20, 1936,Serial No. 59,899

1 Claim.

The use of manganese naphthenate as a siccative in linseed oil paints iswell known, as is the method of manufacture of the naphthenate by doubledecomposition between the sodium salts of naphthenic acids and awater-soluble manganese salt such as manganous sulfate. The mix ture ofmanganese naphthenates thus precipitated contains much free water whichis removed from the gummy manganese soap with considerable difficulty.Up to this time no method for dehydrating manganese naphthenates hasbeen proposed other than to dissolve them in gasoline, filter, orotherwise remove the Water from the dilute solution and distil ofi thesolvent. This method is effective but is unduly costly and unless verycarefully controlled will cause the blackening of the naphthenates atthe temperature required to remove the last of the solvent. Thisblackening always takes place if the attempt is made to remove the waterby heating of the naphthenates without dilution.

I have discovered that manganese naphthenate as well as other highmelting point naphthenates such as those of calcium, magnesium, andcobalt may be dehydrated and rendered useful as light colored siccativesby combining them with lead naphthenates in the drying process, in themanner below described. The product of this drying operation is amixture of lead and manganese (or other heavy metal) naphthenates usefulfor many purposes.

The first step in this operation is to prepare a suitable quantity oflead naphthenate. This step may be performed in any desired manner, butI prefer to carry it out in one of the ways described in my copendingapplication filed January 20, 1936 under Serial No. 59,900, which haseventuated in Patent No. 2,071,862, issued February 23, 1937, by directcombination of the naphthenic acids with lead monoxide. In thisprocedure I first thoroughly moisten the dry powdered lead oxide withsome liquid which will be useful or at least harmless in the finishedproduct, as for example a White petroleum distillate of 40 to 45 A. P.I. gravity and a distilling range between 300 and 400 Fahr. The leadoxide should be agitated with this liquid until each grain is dampenedas, if the acids are allowed to come into contact with the dry oxide,lumps of the oxide enclosed in skins of the lead soap will be formed andthese lumps are practically impossible to break up.

Having first determined the saponification number of the particularnaphthenic acids which are to be used, a stream of the acid is fed intothe mass of dampened lead oxide with constant stirring until themolecular equivalent has been introduced. Stirring may then be continuedin the cold until the reaction is complete. The temperature is thengradually raised to say 250 Fahr. with constant stirring until the waterwhich is the only secondary product of this reaction is entirelyvolatilized. The product is a viscous, semi-liquid mass having a colorcorresponding to that of the acids from which it was made, that is, thecolor does not darken during the drying.

The heavy metal naphthenate is prepared by double decomposition in thewell known manner above mentioned and should be thoroughly washed withwater to remove as much as possible of the water soluble sodium saltresulting from the reaction. The washed mass, which is of a gummy,gelatinous consistency, may be rolled or kneaded to remove excessivequantities of entrained water and may, if desired, be spread out in thinsheets or layers of fragments for air drying to further reduce the watercontent. However, even after this air drying operation is carried tocompletion the water content will still be relatively high,

Either with or without drying as described, the heavy metal naphthenateis now fed into the hot semi-liquid lead naphthenate, maintaining thetemperature of this bath not below 250 F. and preferably in the rangebetween 250 and 300 F. At this temperature the water is rapidly drivenfrom the heavy metal naphthenate, with much less frothing than might beanticipated, probably because of the fact that the high specific gravityof the metallic naphthenates keeps the water at the top of the bath. Theoperation should be performed in an open top kettle with constantstirring until the desired quantity of heavy metal naphthenate has beenadded and desiccated. The total quantity of manganese or other heavymetal naphthenate added in this manner should not exceed about one-thirdof the quantity of lead naphthenate in order to obtain a product whichhas not been discolored by heating.

The product of this operation is a mixture of lead naphthenate with thenaphthenate of manganese or other heavy metal and finds its principaluse as a siccative, for which its pale color and its high oxygenconveying power strongly recommend it.

Iclaim as my invention:

The method of producing mixed anhydrous naphthenates of heavy metalswhich comprises: establishing a body of lead naphthenate at atemperature not less than 250 F. nor greater than 300 F. and maintainingsaid body at said temperature while introducing thereto a hydrousnaphthenate of another heavy metal.

GERALD M. FISHER.

